Thanks! Yes, these were made by Schaller. I’ve already found and ordered single schaller tuner on eBay (used). I’ll replace the part with Hamer logo, so in the end there should be no difference at all
There were some custom Californians with 24 frets. For example one of HFC members owns these nice Californians:
https://www.facebook.com/share/p/1BkRGn7oCX/?mibextid=wwXIfr